Courtesy of Chris Fenton, a research forensic recording of an 80 megabyte CDC-9877 disk pack.
From Fenton: "It is a 'magnetic image' of an 80 megabyte CDC-9877 disk pack that might potentially contain some Cray-1 system software (it might also be blank), of which no known copies currently still exist. I managed to acquire a disk drive from the 1970's that could accept one of these disks, but none of the control electronics worked anymore. I built a robot that manually steps the read heads forward, and then I fed the output directly from the analog sensor into an ADC and buffered it using an FPGA, recording ~4 revolutions of the disk for each head/step. I have approximately 55,000 files, each ~650 kilobytes, of the form "head_#_step_#.dat" that each contain a ~67 millisecond snapshot (the disk is revolving at 3600 RPM, so 1 revolution = 16.67 mS) of the digitized output of the analog read sensor. I need to do a fair amount of signal processing to try to recover data on it, but I'd like a way to share the data with others that might be interested in taking a stab at it."